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Biology Research

Jon Seal Research

OverviewJon Seal 1

My research is broadly integrative by investigating biological phenomena across ecological and evolutionary scales. I have a strong organismal focus on ants, especially fungus-gardening ants. I do this for several reasons. First, fungus-gardening ants like many other ants are very important members of low to mid latitudes in most terrestrial regions of the nearctic and neotropics. These ants often occupy important keystone and ecosystem engineering roles. Second, the study of the obligate symbioses exhibited by the fungus-gardening ants provide windows into the evolution of so-called 'super-organisms' or the merger between vastly unrelated organisms. The obligate symbioses between the ants and their fungi are not unlike the first intercellular fusions that led to today's mitochondria and chloroplasts, which were essential to the evolution of all subsequent multicellular life on earth. Finally, I agree with the NSF and other organizations that realize that many of the biological problems—spanning from those in research, education and policy—can only be solved through a comprehensive understanding of the organisms themselves (Bioscience 60: 673-674).

My research consists of two broad areas:Jon Seal 2

The first addresses the behavioral and physiological mechanisms within the 'superorganisms' (social insects and their symbioses). This corpus attempts to understand how complexity emerges from individuals that arguably have rudimentary cognitive systems (such as ants) and their interactions with organisms that lack any (fungi and other microorganisms).   Second, this knowledge is then used to understand how these mechanisms relate to fitness and how these organisms may interact with and respond to a dynamic environment. Both themes employ a 'bottom-up' method where I search for patterns that can be used to increase if not change our conceptual understanding of the evolutionary and ecological importance of obligate symbioses.

To address these issues I use laboratory and field experiments, quantitative field studies, and Jon Seal 3molecular and physiological methods. This approach reflects my personal fascination with all levels of biological organization, from genes, to physiological processes, individuals, groups to landscapes and regions. Much of my research has been funded by the National Science Foundation.

Major Research Threads

1.      Functional ecology and behavioral physiology of obligate symbioses

This thread addresses the functional organization of the fungus-gardening ant symbiosis. One of the hallmark features of the fungus-gardening ant symbiosis is profound fidelity between the ants and their fungi at higher evolutionary scales. Aside from a few exceptions (as is always the case in biology), clades of ants are usually found with certain clades of fungi. This is thought to represent a classic case of 1:1 coevolution and suggests that there are adaptive features between certain ant-fungal combinations. However, some of my experimental work has made this conclusion somewhat tenuous, since fitness effects associated with symbiont switching is ambiguous at best.   We investigate the role that fungal enzyme physiology and disease may have on constraining ant-fungal combinations in nature. Other significant topics include how learning and imprinting influence worker behavior and also how ant behavior influences colony-level properties.

Accomplishments:

  • Seal JN, Mueller UG. (in review). The collapse of a superorganism: weeds take over the gardens of ants growing novel crops. Evol Ecol
  • Seal, J.N. , J. Gus & U. G. Mueller. 2012. Fungus-gardening ants prefer native fungal species: Do ants control their crops? Behavioral Ecology 23, 1250-1256
  • Seal, J.N. & Tschinkel, W.R. (2007) Co-evolution and the superorganism: switching cultivars does not alter the performance of fungus-gardening ant colonies. Functional Ecology 21, 988-997.
  • Seal, J.N. & Tschinkel, W.R. (2007) Complexity in an obligate mutualism: do fungus-gardening ants know what makes their garden grow? Behavioral Ecology and Sociobiology 61, 1151-1160.
  • Seal, J.N. & Hunt, J.H. 2004. Food supplementation affects colony-level life history traits in the annual social wasp Polistes metricus (Hymenoptera, Vespidae). Insectes Sociaux 51:239-242.

2. Molecular ecology, phylogeography and conservationJon Seal 4

This research avenue investigates the factors that influence the distribution, evolutionary history and fitness of ant colonies.

I apply a variety of molecular tools and field techniques and experimentation to native ant species. For example, the fungus gardening ant Trachymyrmex septentrionalis is an ecological indicator and possible ecosystem engineer of upland pine forests in Florida. In some areas, populations exist on small habitat islands surrounded by wetter areas of lower elevation. Populations fluctuate according to rainfall patterns; they reach their highest during exceptional droughts when soils are deeper and drier, a pattern unlike most southeastern species that are adapted to high rainfall. These patterns largely reflects the requirements of the symbiotic fungus and possibly the interaction with other microbes and soil types.

I have applied similar methods to understanding the historical phylogeography and dispersal biology of the parthenogenic ant, Platythyrea punctata, which is a common species in the West Indies, the extreme southern US (Texas and Florida), and Central America. The phylogeographic patterns leave signatures strongly indicative of rapid population expansion from the mainland to the West Indies. Mainland populations in contrast are highly dispersal limited, with dispersal occurring only on the scale of meters, making them highly subject to habitat fragmentation.

Accomplishments:

  • K. Kellner, Seal, J.N., & J. Heinze. 2013. Sex at the margins: geographic parthenogenesis in the ant Platythyrea punctata. Journal of Evolutionary Biology 26:108-117
  • Seal, J.N., Kellner, K., Fiesel, P. & Heinze, J. (In Revision). Dispersal barriers and reduced gene flow in a parthenogenic ant in the Mesoamerican Biological Corridor.
  • Seal, J.N., Kellner, K., Trindl, A. & Heinze, J. (2011) Phylogeography of the parthenogenic ant, Platythyrea punctata: highly successful colonization of the West Indies by a poor disperser. Journal of Biogeography, 38, 868-882.
  • Seal, J.N. & Tschinkel, W.R. (2010) Distribution of the Fungus-Gardening Ant, Trachymyrmex septentrionalis during and after a record drought. Insect Conservation and Diversity, 3, 134-142.
  • Seal, J.N. (2009) Scaling of body weight and fat content in fungus-gardening ant queens: does this explain why leaf-cutting ants found claustrally? Insectes Sociaux, 56, 135-141.
  • Seal, J.N. & Tschinkel, W.R. (2008) Food limitation in the fungus-gardening ant, Trachymyrmex septentrionalis. Ecological Entomology, 33, 597-607.
  • Seal, J.N. & Tschinkel, W.R. (2007) Energetics of newly mated queens and colony founding in the fungus-gardening ants Cyphomyrmex rimosus and Trachymyrmex septentrionalis (Hymenoptera: Formicidae). Physiological Entomology, 32, 8-15.
  • Seal, J.N. & Tschinkel, W.R. (2006) Colony productivity of the fungus-gardening ant, Trachymyrmex septentrionalis McCook, in a Florida pine forest (Hymenoptera: Formicidae). Annals of the Entomological Society of America, 99, 673-682.
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